Means for by-passing a fault of a line circuit and for telephoning to railway trains



July 18, 1950 P. N. Boss/ART ET AL MEANS FoR BY-PAssING A FAULT oF A LINE cIRcUIT AND FoR TELEPHONING To RAILWAY TRAINS 7 Sheets-Sheet l Filed Dec. 1l, 1947 nu, www NS SSS@ SLLSLLE. d LS l E zum NES L @ESE Y ESS 7 Sheets-Sheet 2 IN VEN TORS Paul Bossa-rf and Elbep Marlowe Y i 5 THF/H ATTomvz'Y P. N. BOSSART ET AL MEANS FOR BY-PASSING A FAULT OF A LINE CIRCUIT AND FOR TELEPHONING T0 RAILWAY TRAINS July 18, 1950 Filed Dec. 11, 1947 Q@ @C\. M

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0 July 18, 1950 P. N. BossART ET AL MEANS FOR BY-PAssING-A FAULT oF A LINE CIRCUIT AND FOR TELEPHONING TO RAILWAY TRAINS 7 Sheets-Sheet 5 Filed Dec. 11, 1947 1 -J NA m m I l, T. -L vllll. AEM. 55.5% ASQSNANW .Nh Nw QBNSW S NSNM MSS A INVENTORS. Paul Mossarz and Elbel Marlow@ THEIR ATTUHNEY July 18, 1950 P N BOSSART ETAL AND FOR TELEPHONING TO RAILWAY TRAINS Filed Dec. l1, 1947 Afan ferrifazy ,Wm/i011 Il 7 Sheets-Sheet 4 E W N5 l u r2 n A s N3 A o, .s d 41 WF .w wm 5 Tf1 \m b: m A b1 Q .s -1 m: Q

m? m Q s a Qa 'n Rm, l g S5 l, ll@ g5 E* INVENTORS.

,s Paul N Bossarf and zbmfzow@ BY Q THEIR ATTORNEY P. N. BOSSART ET AL MEANS FOR BY-PASSING A FAULT 0F A LINE CIRCUIT July 18, 1950 AND FOR TELEPHONING T0 RAILWAY TRAINS 7 Sheets-SheecI 5 Filed Dec. 1l, 1947 July 18, 1950 P. N. laossART Er AL MEANS FDR BY-PASSING A FAULT OF A LINE CIRCUIT AND FOR TELEPHONING TO RAILWAY TRAINS 7 Sheets-Sheet 6 Filed Dec. l1, 1947 DENN v d IIIImu/lhmll M W H am .I n ,vm 0 m ||L mlm w J.. a E @w E w WMM M MSSN i .SQ m5 /Q ,9 l ESB@ N. H E mm In m -1--.. VQ@ .m um T T www @NN P 9% HI|\ w III SE I: A f i .IIDDIII w lum N5 mmv; S VG wm@ NSMW N si@ il 1 Mum. AN U& )Il url) )m P NS NEN. mwwmmw m. 6, wmxm. N N \Q mmv@ @O HM NE u Sgam/@mgm 'July 18, 1950 P. N. BossART ET AL 2,515,855 MEANS FOR BY-PAssING A FAULT oF A LINE CIRCUIT AND FOR TELEPHONING TO RAILWAY TRAINS Filed Dec. 11, 1947 7 Sheets-Sheet 7 "Asgl'f Es 1J J A. l AT YI* w" g E @A A .g5 b t ,5 E S @im v-vv. J g L.- u 5ml al L1 imm-WI A w DAL S4 Lvwmi JNVENToRs. f\ Paul M Bossam and El W Emmi Maplawe q BY l M W15/12 ATTaHNEY Patented July 18, 1950 MEANS FOR'BYLPASSING A FAULT OF A LINE CIRCUIT AND FOR TELEPHONING T RAILWAY TRAINS Application December 11, 1947, Serial No. 791,070 l 4 Claims. (Cl. 179-25) Our invention'relatesV to means for by-passing a fault of a line circuit and for'telephoning to railway trains, and more particularly to such means of the inductive carrier type.

.A line circuit' is generally provided along a railway for a train dispatcher to use in issuing train orders and sending messages. Such a line circuit is frequently a two-wire telephone circuit and the circuit is looped through each of several wayside stations [or towers spaced at intervals along the stretch of railway under the supervision of the dispatcher, `operators at the towers being given train orders by telephone for delivery to train` crews as required. The dispatcher' calls the different towers through a selectorringing system, each tower being assigned an individual calling code which consists ,of a preselected arrangement of pulses of current. The dispatchers oiilce is generally at a division terminal of the railway and not infrequently his office is remote from the territory under his supervision.

With a broken line wire of such a telephonev circuit or if the pole line is down due to a storm, then the dispatcher is without connection to towers beyond the fault and trains may be seriously delayed for want of train orders. This condition is especially true in regions where snow and sleet storms occur.'

Again, the operation of trains may be speeded up if the dispatcher can at times talk directly to the crew of a train en route, and also if each of the operators at the several towers along the railway can talk directly to train crews in the vicinity of his tower.

Accordingly, a feature of our invention is` the provision of improved means for by-passing a fault of a line circuit.

A further feature of our invention is the provision of anovel and improved inductive carrier system for by-passing a fault of a line circuit.

Again, a feature of our invention is the provision of an improved inductive carrier communication system for railway trains and which systemmay be used for by-passing a fault of a tele` phoneline circuit of the railway as well as for telephoning to trains en route.

l Amore specific feature of our invention is the provision of an improved inductive carrier train Other features, objects and advantages of ourv invention will appear as the specificationprol'ess'esq; H 'f 4 The foregoing features, objects and advantages of` our invention we attain by the proivisions of equipment for a 'duplex inductive carrier telephonesystem. Each of several 4selected stations or towers along the stretch of railway involved is provided 'with a transmitter and a receiver ofthe carrier communication system and which apparatus is electrically coupled to a transmitting channel that includes a conductor paralleling the tracks. In an electrified territory of a railroad using a trolley wire, the trolley wire is preferably included in the transmitting chan'- nel because it is not easily torn down by storms or other conditions dueto its .relatively rugged construction.

We provide each towerv with switching means wherewith the operator can connect his inductive carrier communication equipment onto the dispatchers two-wire line circuit. This switching means is also arranged so that it can open the two-wire linel circuit in either or both directions from the station. Thus, if the section of the dispatchers two-wire line circuit between any two. towers is in trouble the stations at the opposite ends of the section in trouble can connect their inductive carrier equipment to the good end of the line circuit, and disconnect the section in trouble. When this set-up is made, the voice frequency current received at a tower from the good end of thetwo-wire line circuit isapplied to Ithe inductive carrier equipment where it is `converted to a carrier telephone current having the original voice frequencies of the voice frequency current. The carrier telephone current is supplied to the transmitting channel here assumed as including theftrolley wire. At thetower at the other end of the line circuit section in trouble the carrier telephone current is picked up fromv the trolley `wire through the inductive carrier equipment and demodulated to produce a corresponding voice frequency current which is thenv applied to the good end of the two-wire line circuit leading from that tower. inductive carrier system serves as an emergency link to by-pass the fault in the'dispatch'ers two-` wire line circuit. 1 Y

Any. one, some or all of the trains operating through this stretch of railway are provided with inductive carrier communication equipment which is coupled to the trolley wire. Thus the dispatcher can talk directly .to any train crew i through the inductivecarrier equipment by hav'- ing the operator at the tower near the train with which' he wishes to talk' connect the inductive carrier equipment of thatA tower onto the dispatchers line circuit;

In this lway thev ach tower or station is also provided with a control panel that includes a microphone and a loud-speaker, as well as control switches therefor andrea@ Operai@ @an @suple his. inductive carrier equipment t9 the trolleygvwire for communication with trains near that station.

In order to preserve the selective ringing func..-` tion of the dispatchers telephone line circuit through the inductive carrier system, the, dispatchers oiiice is providedrn onciorm Qi. our invention with a voice frequency transmitter and at least one of the wayside` stations, which is preferably the station mostremotefrom the dispatchers ofce, is provided with a voice frcquency receiver and a coding vrelay means.` When the dispatcher wishesjtouse the` inductive carrier system for calling he switches his voice ratus embodying the invention when applied to an electrified territory of a railway and when polar relays are used for selective calling of stations Fig. 3 is a diagrammatic view showing a railway division having a relatively large number of wayside stations or towers to illustrate the operating characteristics of the apparatus of our l its, utility.

frequency transmitter in multiple with. hisI y standard selector calling device and pulses of vcicefrequencyenergyfrom thevoice frequency transmitter are, transmitted alongwtli the usual pulsesbf calling, cur ent. The A usualcalling current, pulses eilectiveas far, as theline circuit l thel voice freguency energyserves he output of the transmitter ofthe Y .ii systematthe tower at Whh thesystemj connected tothe two. Wire line circiiitandthecall is sentfout on the inductive car- 'rerSi/s ,Lto .he pitted lip by the inductive carrier` re` ive'r at'the station' beyond the break in the tvvo-wireA lineY circuit.k The carriermodulated bythe callingv voice yfrequency pulses is demodu-v leise, and. the.: voie@ frequency, muses are then transmitted to the station at 'which the= voice fr,eguenzy.receivery is provided. Here it is detectedto'operate the coding relay means. The

operation` of the coding relay means creates pulsesorfcalling current similarV to those,y created atthe'dispatchensofficez by his automaticZ calling A. ,V device. Thesecallingpulsesof current at theV remote, station are reappliedwto the line circuit for actuating the standard selectors atvstations beyond the ,break in the line circuit.

Inanother form of thel invention polar relays are provided at kth`ediifi`erent stations.` One relay responsive'to the` usualpulses/of the calling currentiinterrupts the OutputoLtheVtransrnitter of thlecarriernequipment ofthe sameI station so that whenthe carrier'eguipment is connected to the disdatchers line. circuit pulses of the, carrier corr responding, tothefpulsesfof the original calling currentfare sent out. on the inductive carrier SySilm Qthrlrelays made bearable. inresponse. toftheenergyfpassed by the` receiverfof vthe carriereguipment are provided and these relays are operated)in,stepy withthe interruptionspof the carrier. Thuspthe, interrupted carrier picked upv at'anstation beyonda break in the line circuit serves to operate 'theserelays made operable from thereceiverandthese relayswwhen code operated reapply pulses of calling current back on the line circuit forselection of the stations beyond they break or jthe line circuit.

We shall describe two, forms of `apparatusernbodying our inventiton and shall then point outl the novel yfeatures thereof in claims( In theaccompanying .drawingsFig s. 1a, 112,. 1c, and 1d when placed A`together in the. order named, with Fig, 1a atthe left. are a diagrammatic view showing one form otapparatus embodying our invention whenI applied to an electrified territory of arailway.

Figs. 2.a, 2b, and. v2c when, placed together in the order named withtF'ig. Zaattheleit, are a. diagrammatic View showing another' form of appa;

An: application Serial No. 743,681, filed April munication System for Vehicles, and of common ownership with the present application, discloses andI claims means wherewith inductive carrier communication equipment at a wayside station is remotely controlled from an olce and which eguipmentis broadly similar to the structure of the.A present case.

In the diierent views like reference charactersare used to designate similar parts.

Referring to Figs. 1a, 1b, 1c, and 1d, the reference character TR designates a track of a division Qtay railway. This railway may be a single track line or the track TR may bel one track ofa multiple track road. The division maybe of any given length and it will beconsidered as being of the order of 1'75 miles long, Ashere disclosed a given stretch intermediate the two terminals of the division is an electried territory although the full division ,may` be electrified. In,l

vided for supplying`v propulsion current to the.

trolley wire. The. trolley wire. TW willbe suspended on cantilever arms secured to polesV along the track or in any of the .other standard arrangements for suspending a trolley wire above til-@track rails.

lTraffic over this division of railway is governed by train orders. issued by adispatcher locatedv at anoiicev designated OF. This office may be at any suitable location and it is here shown asbeing locatedatthe west or left-handend of the division.` The trainorders are issued by telephone and a dispatchers telephone Lline circuitA including IineWires-,Ll andA L2 extendsthe. full length ofthev division. This telephone circuit is of thestandard formvusing voice,A frequency currentvand the line circuit-is looped through wayside stations or, towers spaced at intervals along theA railway, the numberanddocations offsuchy stations depending upon the, passing sidi-ngs, yards, :tunnels and other'conditions of: the'railway. In the drawings, vetowersor stations are shown, this number being suiicientfor aful1 understanding ofthe apparatus, but it will be understood that a much largernumber of stations will lordinarily` be provided. Of these vey stations-,a first station SI is located-between the dispatchers ofcefa-ndgthe; near end of the electriiiedzone, the station Si -being illustrative of stationsor towers `along this non-electriedpor-- tion of the division. Stations S2, S3 and Starev shown as being located at the west end,v.an Ainter-l mediate pointand theeast end, respectively, of the electried zone. That is, station S2 is Vthe iirst station in-the electrified zone from the oce OF, station S3 isillustrative of stations spaced at `intermediatepoints along the electrifiedy zone and stationSll is thelast and most remote station in the relectrified zone from the cnice. The fth station S5 is illustrative of stations spaced along the, non-electrified section of thefdivision to theeastoi the electriiied zone. The standard telephone equipment `at the offce OF .and at each of the stations for the dispatchers telephone line circuit ywould be of standard arrangement and it is shown conventionally for ythe sake of-simplicity since its specic structure forms no partof our invention. Furthermore, a conventional form l of selector ringing for .the telephone line circuit `is provided wherewith the dispatcher `can callA any one of the stations. `Itis sufficient for the present application to point out that this selector ringing means includes a battery I0, a key or automatic ringer i I, and a filter network l2 at the oiTceOF, and a selector` ringer dentiiied by a proper legend at each of the stations. rI'he arrangement is such that when the `key ordevice lvl is actuated `the battery ID is connected to the line circuit through pole changing contactsof the device ll `and the circuit network l2 and, current pulses of alternate polarity are supplied to the line circuit for selectively operating the station ringers according-to the code of the callingcurrent. i

Itis to be pointed out that in looping the telephone line circuit through each station jacks are provided for terminaling the line wires to the east of that station and also for terminaling the line wines to the west. These jacks are `designated JW andJE plus numeral suffixes and those for the stations` S2, S3 and S4 of the `electrified zone` are the only ones shown in the drawings since the jacks at these stations are the only ones involved in the present invention. Other jacks designated J` plus a `numeral are provided for connecting .the inductive carrier equipment to the line circuit. The jacks are disclosed in the usual conventional manner and the line circuit is normally connected through each station and can be disconnectedto the east or to the west of the stations by inserting plugs into the proper jacks asV will be readily understood by an inspection of the drawings. Also connection of theline circuit Ll-LZ to the station equipment canbe made by inserting plugs into the proper jacks.

It is apparent that a breakin either of the line wires Ll or L2 or if the pole line carrying these vwires is,y down to groundthe wires, the dispatcher will be without communication with the stations to theeast of the fault. According to our invention we provide equipment for an inductive carrier telephone system which can be used for an emergency link to by-pass such a fault in the usual line circuit and which inductive carrier system can also be used for` communication with trains en route. As here shown this inductive carrier communication system applies to only the electrified zone but it can be applied to other portions of the division. r n

Inductive carrier communication systems of the type here contemplated utilize line -wires and other conductors paralleling the track as elements of a transmitting channel `for conveying the communication energyU along the railway.,Y Thatis, a conductor paralleling the track railsr isan' element` orga transmitting channel due tothe;v

distributed impedance `of the conductor to ground and to the rails.A `In the present disclosure the trolley wire is used as a transmitting channel of an inductive carrier system, this use of the trolley wire being in addition to its normal use. and withoutinterference with the propulsion current system. It is to be observed that the suspension wires for the trolley wire and the associated power cables, .not shown, may also aid in this transmitting channel. The trolley wire is particularly `suitable for use as the transmitting channel for the inductive carrier system because its strength and rugged suspension make it unlikelythat it will be destroyed or torn down by storms `and other conditions, whereas the usual telephone wires may be wiped out by such a storm.` i

The inductive carrier communication equipment may take different forms and preferably it is of the type disclosed in an application `for Letters Patent of the United States, Serial No. 575,311, led January 30, 1945, `now Patent No. 2,484,680, granted October 11, 1949, by Paul N. Bossart, for Railway Train Communication Systems, when the equipment of'that application is modiiied to constitute a single channel duplex system using a iirst carrierfrequency for transmission in one direction and a second and different carrier frequency for transmission in the other direction. By way of illustration, we shall assume that carrier frequencies of f I and f2 for transmission to the west and to the east, `respectively, are used.

The inductive carrier equipment of each wayside station is electrically coupled to the transmitting channelby being electrically coupled to the trolley wire, and similarly the equipment provided on each train is electrically coupled to the trolley wire. 1

Each of the stations S2 and S4 is provided wit a transmitter and a receiver'for the inductive carrier system, these devices being designated by the reference characters T and R, respectively,v

plus a suiiix fl or f2 to indicate the carrier frequency with which it is used. Thus, the rst or west station S2 of the inductive carrier system is provided with oney transmitterTfZ and one receiver Rf I because at this station transmission is to the east only andA reception is from the east only. Similarly, at the last or east station S4V of the system there is provided a transmitter Tl` and a receiver Rf2 because at this station transmission is to the west only and reception is from the west only.

Intermediate station S3 as well as all other intermediate stations that may be provided for the system, are provided with two transmitters Tfl and Tf2 and two receivers Ril and Rfz because transmission and reception at an intermediate station may be either to the east or to the west. i y

These transmitters and receivers vare shown conventionally since they may be anyone oi'I several known forms and preferably'these devices would be similar to the corresponding devices of the aforementioned Paul lN. vBossart application except each transmitter is arranged for use with a single carrier frequency whereas in the Bossart` application a single` transmitter is adjustable for use at either ofthe two carrier frequencies.

The transmitters and receivers at each station are coupled to the trolleywire through an inductive-coupling `which includes a wayside-conductor strung on the same poles thatcarry the trolley wire and `which conductor extends for? at' 7 distance Ito one side v"of the station, adi's'tance of, s'ay i600 lfeet, 'although other 'lengths "of the conductor'c'a'n be used.

ILooking at station S2, for'example, -an input transformer TI for Vreceiver -Rfl has a primary winding I4 onet'erminalof'fwhich'is connected to ground and the other'terminal of which is connected to 'a wayside conductor `'WCI strung relatively close to the trolley Wire TW, the *free en'd'of conductorWCI being preferably grounded. Af`secondar'y winding I 5'of anvoutpiit'trans'former T2 of transmitter Tf2 of station S2 is connected toithe wayside conductor'WCI and ground in multi-plewithprimary winding I"4 of transformer TLthe connection of secondary winding 4`I 5 'prefera'bly including a "capacitor i I 6.

The couplings of the transmitters and receivers at stations S3`and S4 will fbe readily apparent by'an'i'nspection'of vthe drawings when considered withthedes'cription'of the coupling at station in thetrackv layout here disclosed 'effective trans mission from station S2 to tation .S3 and -between stations S3 and Sd lis 'obtained although effective transmission may not'be 'always ob*- tained between station S2 and stationfSd.

Each station S2, S3, and'Sll is provided with a hybrid coil and switching means as -well as the laforementioned vjacks for connecting "the transmitter and receiver of the inductive carrier equipment onto' the dispatchers line circuit LI-L2, the 'arrangement Ibeing s uch lthat with the 'connections once set up the dispatcher can use the inductive carrier equipment at the station without further attention on the part of theopera'tor. 'The switching means is mounted on a 'control Vpanel that also includes a telephone set, the connections of 'such control panel with the corresponding station equipment will be more 'fully explained "when Vthe operation of the apparatus is described.

In order to preserve 'the' selector ringing'function 'fromfthe vdispatchers office through the inductive carrier equipment, a 'voice frequency transmitter'indicated as 'a whole by the refer* ence character V'I isprovided 'at 'the ofi-ice OF and a corresponding and cooperating voice frequency receiver and coding relay means indicated as a wholeby a dotted'rectangle VR." are provided fat station S4. u"I'hesedei'fices VT at the'oflice and VR at the station S4 will Aalso'be more fully explained when the operation of the apparatus is described.

VA vehicle of a train, such as a"locom`otive,is indicated conventionally at LO, "the "train 'of which this 'locomotive "is a' part being en route in the vicinity of lthe Wayside station S3. 'The locomotive LO is 'provided with inductive lcar4- rier equipment comprising two receivers RI and RfZ 'and a single transmitter designated Tf. These Adevices on the locom't'ntive are 'capable of using the carrier'ffr'equencies here assumed and are'lpreferablyl'of `the "form disclosed linthe beforementionedPaly N. fBoss'art application. The train carried receivers 1Rfl and R`,f2 are iconnected vvtolpick-upcoils vPCI and PC2, respectively, each of which coils Eis mounted on the the locom'o'tive lfor inductive relation with the trolley wire. The? output of the transmitter Tf on the locomotive is connected to a sending loop circuit that is connected -to `two pairsl of 'spaced wheels of thelocon'iotive and 'which loop circuit is arranged forinductive association with the transmitting channel including the trolley wire in the well-knownlmanner for such carrier systems. It is clear lthat the train carried sending and Ipick-up elements may be arranged for capacitance coupling with the trolley wire in place iof'inductive coupling or the transmitters andreceiversv'of the'flocomotive may be both inductively and Ic'apacitively connected to the trolley wire throughindep'endent coupling'units. Other locomotives and other train vehicles of trains v"operating in Ethe electrified territory may be 'provided with inductive carrier telephone equipment similar to-that provided for the locomotiv'e'liO.

In Adescribing the operation of the apparatus of Figs. la, 1b, 1c,"and 1d, We shall first consider 'the'normal condition, 'that is, the condition'fwhen the telephone line'circuit LI-LZ is int-'act throughout 'the division. Under 'this normal condition, 'the dispatcher issues train orders land other'messages to the different-sta- *tions through his standard telephone equipment, 'calling the stations as wanted through the regular selector ringing devices,

The inductive carrier system equipment is in a -stand-by j condition during such normal operation of the dispatchers line circuit. In the Stand-bycOnditiOn ofv the carrier 'equipment the receivers fR 'at each of'the stations and on each of the 'trains are energized and ready 'for reception but the transmitters Iare deenergized and inactive. -At eachstation and on each train a `suitable-source of power for energizing the receiversandtransmitters is provided, such source of :power being here indicated by a positive terminal B300vand aneg'ative terminal'which is connected to ground in the usual manner.

vWe shall next ars'sume that there is a break in one 'or 'both the line wires LI and L2 between stations S2 and Slat a location indicated in Fig."1a. vby a dotted line X. The dispatcher will discover that he is unable'to lcommunicate with stations east of the/station S2 by his regular telephone equipment. `This being so and the dispatcher wishing to issue'an order to the op- 'erator 'at stationS3, for'example, the dispatcher w'ill Vfirst call up the operator at station S2'by his regular 'telephone Aequipment 'and inform that operator of the fact'fthat 'the line circuit isou'tf'to thef'east of his station 'and the induc- 4"tive 'carrier equipmentw'ill be used to byfpa'ss the fault. The'operator at station S2 inserts 'plug in jack JlII-to disconnect the'line wires LI and'Ii2 to lthe eastv and into jacks J I and 'J2 to "connect the 'line "wires from'the west to wires Tf2 at station S2"`andthat transmitter is energized and madeactive'along'with the already active receiver Ril. With this set-up' at station S2 the dispatcher proceeds to call station S3'and todo so he would ordinarily send over hisregulary telephone s et an agreedY salutation. Considering that the 'ilis` patcher speaks a given salutation" for identifying the stationS3 into his telephone transmitter, the correspondingvoice ltelephone current is" transmitted to station S2 over the good portion of the line circuit Ll- -L2 and at station S2 this'voice current is applie'izl through wires Il and7 l8,`hY brid coil I9, resistance pad 23 and input trans` former T3 to the now activeutransmitter Tj2. The carrier vfrequency f2 of thistransmitter is modulated by the voice current and 'a corresponding carrier telephone current is supplied to the wayside conductor WCI` ytl'irough the output transformer T2 of the'transmitter IJZ.. This current iiowing in the wayside conductor WC l induces a corresponding electromotive` force in the trolley'wire TW and'current flows therein to induce an electromotive force in the vwayside conductor WO2 at station S3, it being recalled that stations S2 and S3 are within effective range of transmission for the inductive carrier system. From conductor WCZ'the carrier telephone 'energy is appliedl to receiver Rf2 at station S3 through an input transformer T4. Since the re` ceiver Rf2 is normally energized andrr'esponsive to carrier telephone current of the carrier i,f2 frequency, this current is demodulated and the voice frequency current is applied to a loudspeaker LS of the control panel CP3 of'station S3, the loud speaker being connected to the out`l put of the receiver Rf2 through transformer TI!) at a reduced sensitivity due to a resistor 24 being connected in series withl the loud-speaker.

The attention of the operator at station S3 having been attracted by this* call from the dispatcher', the operator` would ordinarily close switch 25 of his control panel and Vswitchv the loud-.speaker to its full sensitivity, the closing'of switch 25 also preparing a microphone circuit to be referred to shortly. The dispatcherv would follow up such a call by informingfthe operator at station S3 that there is' "a break in the `line wires Ll and L2 to the westof his station andthe inductive carrier equipment is to be used forcemmunication. flnfview 'of this information the operator' at station S3 would *plug into jack JWI to disconnect the faultyv line Wires LI and L2 to the west. He would also plug' into jacks J3 and` J 4- to vconnect `his-carrier equipment onto the-line' circuit to"'the'feast'. When theplug 'is inserted into' the jackJ4 at'station S3 `a contact 26isk closed to complete'acircuit for energizing control re1`ayf2l whiclilrelay `picks up closing .frontzcon-` tactl andy applying power tothe ytransmitter Tfl at thatfsta'tion; solthat both thelreceiver Rf2 andftransmitter"Tfl:` at `station`S3` are now` energized for communication with the dispatcher.'4 Voice frequency telephone current. of a dispatchers message is supplied at the oiice OF to the line wires-LI and L2; andreceivedat'the'sta-z tionSZr'to be applied totransmitterTfZ land sup-y pliedi to the transmitting channell of thei'nductive carrierfsystem for transmission tf1-station S3 be'-E receiver RJZ through input'transfor'mer'T4 and`w demodulated and the message `sounded in" they loudspeaker l LSF.i 1 In replying to the dispatcher,

. 10 y the operator at ystation S3 would close his switch@ 29 of the control (panel to the left asviewed in Fig, 1b to complete the microphone circuit .which is now connected to the input of `transformer lfyjlv throughinput transformer TI I.` The carrier, fll of this transmitter is modulated bythe voice fre.-l quencies created in the microphone 30 'and y,the resulting carrier telephone current fis supplied l, through output transformer T5 to the wayside conductor WO2 and inductively transferredlto the" trolley wire. This current is inductively picked up fromy the trolley wire by conductor ,WC1 at station S2 and appliedto the input of kreceiver Rjl of thatstation through input transformer Tl. `After ydenvioclulation the voice frequency currentisv applied through'transformer T6, resist'-k ance pad 3l, hybrid .coily I9 and wiresl l1 and ll` to the line wires Ll and L2 for transmissionto the oiiice OF where the voice frequency current isreceived by the usual dispatchers receiving set.

It follows from the foregoing thatthe Vdisf-k patcher and operator at station S3 can carry on al, two-way conversation aroundnthe broken', line, wiresby using `the inductive carrier equipment. at stations S2 and S3, the connectionateach staf" tion once made by the operator requiring' noifufr-g.

ther Vattention onhis part; 4

It is to vbe noted that in place `of the. dispatcher. calling station S3 through l.the inductiveparrier system, he can have the operator at station S2d call the operator at station S3 throughth'eindue-` tive carriervsystem.` 4 f l Assuming'that with the line circuit interrupted at location X between stations S2 and S3 the dispatchery wishes to communicate with Staf tion S4, which station S4 will ordinarily be bef-, yond the effective range of transmissionoffthe carrier system froml stationI S2. In this casethe dispatcher would .first call the 'station S2 and have `the operatorcutfinthe inductive carrier equipment in' the mannerpreviously explained. The dispatcher would thenlcallstationS3 or have y thev operator at station S2 .call the .operatory atv station" S31throgh `the inductive carrier k equipe. ment in themanner explained hereinbefore and.; have the operator at station LS3 disconnecttlie faulty linesectio'n and connect the 'carrierv equip), mentto the line v'circuit to the east in the manner previously explained.` It isto be noted that the output of receiver Rf2 and the input ofisitaris'l-` mitterTfl at station S3 are now connectedfto the une circuit leading te the east of station sa, through a hybrid coil 4B and Ajacks J 3 andy Mythe.. connection `.of receiver," Rf2` including output transformer Tl 0 `and the lconnection of ltransniitter-Tfl'in'cluding inputV transformer TILv With tlie'ninductive4 carrier equipment thus Vcuty in at stations S2 and S3,,thejdispatcher `calls `the operator at station S4 around ,the break' inthe; une 'circuit b'yuse f his` voice -rrequencv traisi mitter VT. The transmitterfVTcomprisesarr oscillatoifOS,V a power amplifier vvtube Y3l', biased polar relay '38,a transfori'nerA I'I3 and isco'n-i nect switch 39. TheoscillatorOS isjshown C0. ventionally and is preferably of the .electroni typ "adaptable ,f Supilyis al grehaiv'oi l quen'cycurrentQ'a voice frequency of theorder off' say"1000 cycles per secondlfThe output of oscillator"QS is capacitance coupled to'jthe `cori-7J trol *grid* of` amplifiertube" 3T.' ''With switcljifl" closed,"termina1 B300 of av-'suitable oicepower source is connected to the oscillator OS andto the. anodef the tuberi, the connection ictneanbde of tube'linoludirlg primary winding 40 of trans-f formerfTl'3; a lsecondary'winding 44 of which 13 cation with the dispatcher byfrst sending a call overthe inductive carrier equipment for reception at the station S3, the crew using the carrier frequency fl. This call is demodulated at receiver Rfl andisounded on the loud-speaker LS of station S3. After such a call is received the crew would inform the operator at station S3 to connect the inductive carrier equipment to the dispatchers line circuit andwhich the operator would do by inserting plugs into the jacks J I and J2. In doing this the operator would rst check by using his standard telephone set that the dispatcher is not using the line circuit for issuing orders to some other station. With the set`up made at station S3 two-way conversation can be effected between the locomotive crew? and the dis.-

patcher at the office in the manner explained hereinbefore. i

Communication between the dispatcher and trains in the vicinity of stations S2 and S4 can be accomplished in a manner similar to that explained in connection with communication with the locomotive LO in the vicinity of station S3. It is to be noted that at station S4 the transmitter Tf! is governed by a control relay 64 which in turn is controlled by a contact of jack J4.

In the event the operator at station S3 wishes to communicate with locomotive LO which is operating within the transmission Vrange of that station, the operator would close` switch" and shift selector switch 29 and switch .61 at his con'- trol panel CP3 to the right. This switching would pick up relay E5 to energize the transmitter `'IJZ and effectively connect the microphone 30 and loud-speaker LS to the transmitter Tf2 and receiver Rfl, respectively. With this set-up the operator could call the train by speaking an agreed call into the microphone, the voice frequencies being applied to the input of transmitter Tf2 and the modulated carrier'f2 being applied to the trolley wire through conductorWCZ for transmission to the locomotive where it is picked up by coil PC2 and applied to the train receiver RfZ. In replying the locomotive crew would `use the carrier fl and the carrier telephone current would be received and demodulated at receiver Rfl of station S3 and the speech sounded at the loudspeaker. Thus the operator at station S3 can carry on a conversation with the` nearby train without disturbing the dispatchers line circuit. The operators at stations S2 and S4 can communicate with trains operating within the vicinity of these stations in a similar manner as explained for station S3. i l l It is to be noted'that a choke'coilcan be installed on each locomotivein the usual power lead from the trolley to 4the locomotivecontrol equipment to preventloss ofi the communication current through the locomotive motors to ground if such loss is found to impair effective operation of the communication system;

' Referring now to Figs. 2a, 2b,` `and 2c,`fthe track i layout and the locations of the dispatchersoice and the wayside stations` are:'theis'ame as'fconsidered for Figs; 1a', lb, lc,;and1d .1y `Also'the` dise patchers line `circuit and thecarrier` inductive equipment are the same as previously described except that the voice transmitterv 'VTrfand' voice receiver VR `aref'omitted and 'polar relays and lters are provided for the carrierequipme'nt to effect the station calling through the `inductive carrier system. The operation'ofthe apparatus Iis substantially thes'ameas inrFigsJr la; lb,^1c`, and 1d `except for thestation .callinganditis believed thatl this calling means .carr'ibest l be" understood from a description of this part of the operation ofthe apparatus. Under normal conditions of the line circuit the carrier equipment of Figs. 2a, 2b, and 2c is in its stand-by condition, the receivers being energized and thetransmitters being deenergized.

Assume that the line circuit is open at location X east ofy station S2 and the dispatcher wishes to call station S3 to the east of the line circuit fault. The dispatcher rst calls station S2 to tell the operator at that station to cut in his carrier equipment, which he does by inserting plugs into jacks JEI, J l, and J2 to disconnect the line to the east, connect the transmitter Tf2 and receiver Rfl to the line circuit to the west and to energize transmitter Tf2.

The dispatcher can thus call station S3 direct by speaking an agreed salutation into his transmitter. The voice telephone current is received at station S2 and applied to transmitter Tf2 to modulate the carrier f2. This carrier telephone current is transmitted over the trolley wire and received at receiver RJZ of station S3. At receiver Rf? the current is demodulated and the salutation is sounded at ther loud-speaker at station S3. With the operator at station S3 alerted the dispatcher can instruct the operator as to the line circuit fault and to connect in his inductive carrier equipment which the operator will do by inserting plugs into jacks JW2, J4, and J 3.

A In place of the dispatcher issuing these orders vdirectly to the operator at station S3, the dispatcher can have the operator at station S2 call the operator at station S3 over the inductive carrier system which the operator at station S2 can do because the receiver Rf2 at station S3 is normally active. The operator at station S2 would then direct the operator at station S3 to cut in his inductive carrier equipment to the line circuit to by-pass the fault at location X.

With the inductive carrier system linked around the line circuit fault the dispatcher can call `any station east of the fault. Assume for example the dispatcher wishes to call station S4 through the inductive carrier system bridging around the line circuit fault at location X. The dispatcher will operate his calling device il as required to send out the code pulses for station S4; These pulses are received at station S2 and operate a biased polar relay 10 connected across the line through jacks J l and J2 in multiple with the input to the hybrid coil I9, so that relay 1i) receives an impulse to reverse the relay each code pulse. When relay 10 is reversed opening its normal contact ll, the transmitter `Tf2 is made inactive. As here shown it is made inactive by the opening of the connection through which it is powered but other arrangements can be used. This interruption of transmitter Tf2 causes the carrier fZtsupplied to conductor WCl and thence to the trolley wire to be coded according to the code pulses sent out from the dispatchers oflice. These pulses of the carrier are received at sta- .tion S3, and applied to receiver Rf2. The receiver .75 and'l4,` the connectionbeing such thatthe relay is :12 iisreversed for 'eachsuchvoltage pulse. A? neutral relay I5 is normally energized through a `normalipolarcontact 16 of relay fTZandthus relay 15 is deenergized as long as the lcarrier is -received Ebut whenrelay -1'2 is code operated in response to code interruption of the carrier lthe relay "i receives an energizing pulse each oir code period of the carrier. Relay is provided 'with a slow release 'period sufcient to retain -the relay picked up as long as relay 'i2 is code 'operated With relay 15 picked up and 'relay 1Q `code operated to operate its pole changing contactmembers 'I1 and '78, direct current pulses 'of alternate polarity -are supplied through a filter `"network 'i9 to the line circuit to the eastvof sta- I tion S3, the connections to line wires LI and L2 `being completed through jacks J4, J3, JE2, 'and JEL It follows that the'callingcodes sent'out from kthe''stli'spatchens oiiice for station S4 are impressed upon the carrier f2 at station S2 and sent out on the inductive carrier system. The code pulses fof 'the carrier `are lreceived at station S3 by the lreceiver Rf? for operation of'relays 12 and V'I5 and calling codepulses corresponding v'to the original code sentio'ut by the dispatcher are reapplied to the line circuit at station S3 for selective opera- -tion-of the selectory ringer at station'Sd. Simi- -larly, the Adispatcher can call any other station to the eastof the line circuit fault.

The station 'S3 is Ipr-ovided with a polar relay -Bwhi'c'h corresponds to polar relay 'I0 of station S2, and -station Sais provided with relays li-'i'and 48 and a iilter 59 which corresponds to'relays "i2 rand 'i5 vand filter 'I9 at station S3 for by-passing 'acall around aibreak in the line wires Ll and L2, between'the stations S3 and S4, the operationbeying 'similar to that explained in 'by-,passing a st-ation call larcund a line circuit break at location X.

'A system such as here disclosed is 'capable of `'by-passing more than one break in the line circuit. Referring to Fig. 3, which discloses a divvision having a 4relatively large number of wayside stationseach of 'which stations is connected to the oiiice through ladispatchers telephone line circuit. Also inductive carrier equipment is assumed as being provided at'each-of the stations fand coupled tothe trolley wire or some other conductor. If these stations of Fig. 3 are spaced apart so that effective transmission for the inductive carrier system is obtained between adjacent stations only, then the equipment could -by-pass-a-break in the line wires between any two adjacent stations the same as explained in connection with `Figs. la, lb, and lc. Also it would Y'be possible to by-pass moreV than one vbreak between stations if the two breaks lare not between successive stations. For exam-ple, the system would by-pass breaks in the line circuit between stations S2 'and SSA of Fig. 3, betweenstations SSB and S3C, 'and lbetween stations SSD and S3E. l

In the event the stations of Fig. 3 are spaced Kso that the effective range for the inductive carrier system is equal to two sections each side vof the station, then two breaks in the line circuit for two successive sections of the line circuit can be by-passed by the inductive f/arrier system.

In the extreme circumstances that the Aline circuit of Figs. 1a, 1b, and lois interrupted between two adjacent sections, such as between stations S2 and S3 and vbetween stations S3 and S4, the two breaks can be by-passed by the inductive 'carrier system by transmitting the message from i16 the dispatcher to the operator'at station S3 and lhaving-the operator-at station S3 repeat the message over the inductive carrier system to station-S4.

'Although we have herein shown and described only two forms of means for by-passing a fault of a linecircuit'and for telephoning to railway Atrains embodying our invention, itis understood Ithat various changes and modifications may be made -therein ywithinthe scope'of the appended lclaims. without departing from the spirit and lscope v of our invention.

Having thus described our invention, what Awe claim is:

1. In combination, ran office, several stations spaced apart to one sideof the oice, a two-wire line circuit-extending from the oice through said stations, station calling apparatus including coding means at the oiiice and a selector at each `of said stations, said cfiice coding means including a coding device land a current source, said coding-means being-connected to said line circuit and-operable to'supply pulses of current of dif- 'ferent'codesea'ch said selector'co'nnected to said line Acircuit and Vincluding means responsive to pulses di current o'f a code individual for the respective station, ycarrier current equipments one 'at each'of sa'idstations, each said equipment in- Acluding v'a transmitter lhaving means for supplying carrier frequency current andA a receiver having means responsive to carrier frequency current, a, transmitting medium for carrier fre- 'quency current and which medium is common to said stations and exclusive to said two-wire line circuit, each "said carrier current equipment having an output lcircuit `of its transmitter and I'an input circuity of its receiver electrically coupled to said transmitting medium, additional station calling apparatus including a rst and a sec- -ond code repeating means at each of selected ones of said stations, each said first code repeating vmeans including means having connections to the transmitter of the same station and to saidA 'two-wire line circuit through a manually oper- 'able.c'ontroller, 'each said rst code repeating -mea'ns being eiective to code the carrier current supplied by the respective transmitter to said 'transmitting 'medium in step with code pulses of current received from said line circuit, each said. second ycode repeating means including means connected tothe receiver at the same station and having connections to said line circuit through la manually operable controller, and cach said second code repeating means being eiiective to lsupply vto the line circuit code pulses of current in step with code pulses of carrier frequency current-received from said transmitting medium.

2. In combination, an oirlce, several stations spaced yapart to one side of the cnice, a twowire line-circuit lextending from the cnice through said stations, a station calling means at said `oilice and including 'a source of direct current and a coding device, said calling means being con- -necteclv to said `line circuit and operable for supplying pulses of direct 'current of diierent codes, a selector at each of the stations, each said selector connected to said line circuit and includin'g means responsive to pulses of direct current of a code individual for the respective station, carrier telephone equipments one at each of said stations and each Vequipment including a transmitter and a receiver, each said transmitter having an input and an output circuit and including means lfor supplying a carrier telephone current toitsv output 'circuit in response to. a, voice ffre- 1'7". iquenic'y 'current supplied toi its input circuit, each said receiver having aninputj and an output circuit and including meansfor supplying a voice frequency Vcurrent to its output circuit in response to a carrier telephone current supplied to its input circuit, a transmitting medium of carrier telephone current-common to all of said stations and exclusive of said-itwo--wire line circuit, each said carrier telephone. equipment having the output circuit of its transmitter and the input circuit of its receiver electrically coupled to said transmitting medium, circuit means at each of said stations and including circuit controller contacts which are operable to a given position to connect the input circuit of the transmitter and the output circuit of the receiver of the same station to said line circuit, an oscillator at said office and including means to supply a given Voice frequency current, means at the office to connect said oscillator to said coding device and to said line circuit for supplying code pulses of voice frequency current of said given frequency to the line circuit, a detector and a coding relayr means at the station most remote from said cnice, said detector connected to said line circuit and including means responsive to current of said given voice frequency, said coding relay means being connected to said detector and including a code following relay, a

source of direct current at said most remote station, and circuit means at said most remote station and including contacts of said relay to connect said last mentioned source of direct current to said line circuit.

3. In a station calling means for a communication system which provides communication between an cnice and several stations which are spaced apart to one side of the ofce and which system uses a two-wire line circuit extending between the oflice and the several stations, the combination comprising, a battery and a coding device at the cnice, said battery being connected to said line circuit through said coding device, said coding device being operable to code the current supplied by the battery according to different codes, a selector at each of said stations, each selector being connected to said line circuit and including means responsive to code pulses of direct current of a code individual for the respective station, carrier telephone equipments one at each of said stations, each said equipment including transmitting apparatus having means operable to supply a carrier telephone current in response to a voice frequency current supplied to the equipment, each said equipment also including receiving apparatus having means operable to supply a voice frequency current in response to carrier telephone current supplied to the equipment, a transmitting medium of carrier telephone current, said transmitting medium being common to all of said stations and independent of said two-wire line circuit, each said carrier telephone equipment being electrically coupled to said transmitting medium, circuit means at each of said stations and including circuit controller contacts which are operable to a given position for connecting the carrier telephone equipment of the same station to said line circuit, an oscillator at said ofce and including means operable to supply current of a given voice frequency, means at the office including a contact of said coding device to connect said oscillator to said line circuit to supply code pulses of current of said given voice frequency to the line circuit, said carrier telei being5effective to transmit said code pulse of voice frequency current between the *stationsl through said transmitting medium independent of the line circuit between the two adjacent stations when the two carrier telephone equipments are coupled to both the transmitting medium and the line circuit, a detector and a coding means at the station most remote from said lofce, said detector connected to the line circuit and including means responsive to code pulses of current of said given voice frequency, said coding means including a code following relay and a battery, and circuit means to connect said relay to said detector and to connect the last mentioned battery to said line circuit through a contact of said relay.

4. In combination, an oiiice, several stations spaced apart to one side of the office, a two-wire line circuit extending from the oice through said stations, a station calling means at said oflice and including a source of direct current and a coding device, said calling means being connected to said line circuit and operable for supplying pulses of direct current of different codes, a selector at each of the stations, each said selector connected to said line circuit and including means responsive to pulses of direct current of a code individual for the respective station, carrier telephone equipments one at each of said stations and each equipment including a transmitter and a receiver, each said transmitter having an input and an output circuit and including means for supplying a carrier telephone current to its output circuit in response to a voice frequency current supplied to its input circuit, each said receiver having an input and an output circuit and including means for supplying a voice frequency current to its output circuit in response to a carrier telephone' current supplied tc its input circuit, a transmitting medium of carrier telephone current common to all of said stations and exclusive of said two-wire line circuit, each said carrier telephone equipment having the output circuit of its transmitter and the input circuit of its receiver electrically coupled to said transmitting medium, circuit means at each said station and including circuit controller contacts which are operable to a given position to connect the input circuit of the transmitter and the output circuit of the receiver of the same station to said line circuit, additional stationv calling means including a first code following relay at each of said stations except the station most remote from the office and a second code following relay and coding means at each of said stations except the station nearest the ofce, each said first code following relay connected in multiple with the input circuit of the transmitter at the same station and being provided with a contact which is included in a circuit that is connected to the transmitter to code the current supplied by that transmitter to said transmitting medium, each said second code following relay connected to the receiver at the same station, and each said coding means including a source of direct current and contacts of the second code following relay at the same station and having connection to said two-wire line circuit.

PAUL IN. BOSSART. ELBERT W. MARLOWE.

(References on following page) REFERENCES CITED YThe'following references are of record in the le of this patent:

UNITED STATES PATENTS Number 20 Name Date Ael Mar. 28, 1933 Espenschied Nov. 7, 1933 Green Nov. 7, 1933 Vincent Feb. 22, 1938 Terroni Apr. 1'4, 1942 Honaman Sept. 8, 1942. Haberl Oct. 16, 1945 Clark Jan. 22, 1946 

